Caption: Stem cell research. Researcher handling chemicals and samples of stem cells. Stem cells are cells that differentiate to form the range of different tissues found in the human body. The type of cell they mature into depends upon the biochemical signals they receive. Stem cells can be obtained from bone marrow, umbilical cord blood and embryos. Stem cells are being studied to find treatments for disorders of the blood and organs such as the heart, brain and kidneys. This work is being carried out at the Stem Cells Research Institute (SCRI) in Milan, Italy.